Module 4 - Operating Parameters

Module from the Hydroprocessing Operations Curriculum curriculum.

OPERATING PARAMETER OPTIMIZATION · Learning Objectives · 1. Calculate WABT (Weighted Average Bed Temperature) for multi-bed reactors 2. Optimize LHSV for target conversion and catalyst life 3. Understand H2 partial pressure effects on reaction kinetics and catalyst stability 4. Set quench ratios for temperature control and bed ΔT management 5. Monitor key performance indicators during normal operation · Key Operating Parameters by Service

Parameter	Naphtha HDT	Diesel HDT (ULSD)	VGO Pretreater	Mild Hydrocracker	Full Hydrocracker	Units
WABT (start of run)	550-600	620-660	680-720	700-740	700-730	°F
WABT (end of run)	620-660	700-740	740-780	760-790	760-790	°F
Deactivation Rate	0.5-1.5	1.0-3.0	2.0-4.0	2.0-5.0	1.5-3.5	°F/month
LHSV	3.0-6.0	1.0-2.5	0.8-2.0	0.5-1.5	0.5-1.5	hr⁻¹
H2 Partial Pressure	150-400	400-800	600-1200	600-1200	1200-2500	psig
H2/Oil Ratio	500-1500	2000-5000	3000-6000	3000-6000	5000-10000	SCF/bbl
H2 Consumption	50-200	200-600	400-1000	600-1200	1200-2500	SCF/bbl
Reactor ΔP (clean)	5-15	10-30	15-40	15-40	20-50	psi
Reactor ΔP (fouled)	15-40	30-80	40-100	40-100	50-120	psi
Typical Feed Sulfur	50-2000 ppm	0.5-2.5 wt%	1.0-3.0 wt%	1.0-3.0 wt%	0.5-3.0 wt%	ppm or wt%
Product Sulfur Target	<0.5 ppm	<15 ppm	<500 ppm	<500 ppm	<15 ppm	ppm
Cycle Length	3-5 years	2-4 years	1.5-3 years	1-2.5 years	2-4 years	years
WABT Calculation Method
Element	Formula	Example (3-bed reactor)	Inputs Needed	Where to Find Data	Notes
Bed Average Temperature	T_avg = (T_inlet + T_outlet) / 2	Bed 1: (650+690)/2 = 670°F	Inlet and outlet TCs per bed	DCS historian, reactor TC panel	Assumes linear profile (not exact for deep beds)
Bed Weight Fraction	f_i = catalyst_weight_bed_i / total_catalyst_weight	Bed 1: 12,000 lb / 36,000 lb = 0.333	Catalyst loading report	Loading report, catalyst BOM	Use actual loaded weight, not design
WABT	WABT = Σ(f_i × T_avg_i)	0.333×670 + 0.333×680 + 0.333×695 = 681.7°F	All bed averages and weight fractions	Calculated from above	Single number representing reactor severity
Normalized WABT	Adjust for feed quality changes (S, N, density)	Correct for feed sulfur: +2°F per 0.1 wt% S increase	Feed lab data, baseline conditions	Lab results, operating procedures	Allows apples-to-apples comparison over cycle
Source: FOS Chief Files — Hydroprocessing Design Manual, WABT_Calculator_v1.xlsx, HCU_Cycle_Data_Review_v1.xlsx

Source: Hydroprocessing_Operations_Curriculum_v1.xlsx · Sheet: Module 4 - Operating Parameters

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